Fixed-angle variable-range marker launcher



- June 20, 19 E. w. JOHNSON, JR, ETAL 3,326,082

F1XED-ANGLE VARIABLE-RANGE MARKER LAUNCHER Filed Sept. 50, 1965 7 I 22 I I5 4 IO Q 40 M I LA 11mm ET fl i fl 6 36 ...III I aa I I a") II c fi ffis I 1a III| NETWORK g: I \d I U R 40 II I Hum I II C R I I I? I3 F I 2! I 44 7 -2o 1 I ii I z I BEARING I *1. M AMPLIFIERI I 1 I I I f I I SONAR xoucsn I ,9 I I M 46/L J FIG. I fCABINET 'l I (050k INVENTORS EDWARD w. JOHNSON, JR. y JAMES M. .SEAWR/GHT aux:

A TTOR/VEYS United States Patent flee 3,326,082 Patented June 20, 1967 3,326,082 FlXlID-ANGLE VARIABLE-RANGE MARKER LAUNCHER Edward W. Johnson, Jan, and James M. Seawright, Panama fifty, Fla, assignors to the United States of America as represented by the Secretary of the Navy Filed Sept. 30, 1265, Ser. No. 491,849 3 Claims. (Cl. 89-1) ABSTRACT OF THE DHSCLOSURE The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

The present invention relates to variable-range projectile launchers of the rifie-grenade-type and more particularly to such launchers which under the control of a ships sonar can propel a marker projectile through an airwater trajectory to a point on the ocean floor near a sonar contact which has been classified as a mine.

In certain mine hunting operations a sonar equipped search ship proceeds through an area thought to be mined until a contact is detected. Thereafter the ship for the sake of safety remains at least 100 yards from the contact until it can be classified as mine-like or not and when appropriate marks the location of the mine-like contact for later neutralization while the ship continues to search for new contacts.

In accordance with the present invention the marker luncher has a fixed elevation angle, and range is varied by adjusting a gas venting valve to vary the pressure acting to accelerate the projectile (marker). Also in accordance with the invention the launcher is automatically controlled in range and hearing by the ships sonar.

Known method employed for varying range in launching military rifle grenades and in the firing of mortar shells include in both cases the varying of the elevation angle of the ride and mortar barrels. The desired accuracy of the present launcher suffers, especially at short ranges, from the use of such range varying practices because at short ranges the elevation angle becomes very high or very low resulting in correspondingly very high or very low trajectories. The high trajectory results in a long exposure to wind while the low trajectory may cause the projectile to richochet on a rough water surface.

It is also known in antisubmarine warfare for launch ing relatively heavy depth charges to employ adjustable exhaust gas venting structures to vary the range of a missile fired from a projector having a fixed barrel elevation.

An object of the present invention is to provide a launcher for a relatively light weight marker having variable range and bearing controls coupled to a ships search sonar for marking the location of a sonar target which has been classified as being mine-like.

Another object of the invention is to provide a simple arrangement for controlling the venting to the atmosphere of gases from the propellent explosive for varying the range of a projected marker.

Other objects and many of the attendant advantages of this invention will be readily appreciated by those skilled in the art from the following description when read in connection with the accompanying drawing in which:

FIG. 1 is a side elevation partly in section of a preferred embodiment of the invention; and

FIG. 2 is a fragmentary sectional view of an alternative gas venting arrangement.

Referring now to the drawing wherein like reference characters denote like parts in the two views, FIG. 1 illustrates a preferred embodiment wherein a firing mechanism 10, here shown as comprising a modified rifle, is provided with a barrel 11 which fits into the tail tube of a projectile 12 which in the presently intended use comprises a marker of known construction and operation for identifying the position on the bottom of an underwater mine-like target. The firing mechanism 10 is mounted on a frame 13 which is gimbal-mounted with freedom in two orthogonal vertical planes on a support arm 14 by means of a Y-shaped yoke 15 the primary shaft of which rotates freely in a bearing 15 provided on the arm 14 and the two secondary shafts of which engage trunnions 16 provided on the barrel 11 in a well known manner. The frame 13 comprises two spaced parallel plates the front one as viewed in FIG. 1 being omitted for the sake of clarity. The frame 13 has secured thereto as by bolts 40 a pendulous weight 17 for utilizing the force of gravity to tend to maintain the orientation of the frame 13, and hence of the barrel 11, with respect to the vertical during angular movement during pitch and roll of a ship the deck 41 of which supports a cabinet 42 which mounts the support arm 14 for rotation about a vertical axis. In order to make the gimbal-mounted assembly relatively insensitive to angular movement of the ships deck 41 it is designed to have a natural fre quency, say one cycle per second, which is high relative to the frequency of the ships movement. Preferably the gimbal-mounted assembly including the pendulum 17 is so supported that the rifle barrel 11 will assume a 45- degree elevation when loaded with a marker projectile 12. This assembly is moved as a unit to train the barrel 11 in bearing by a servo motor 18 which rotates the support arm 14 through gears 19 to the azimuth of the ships sonar transducer through a synchro control transformer 20 adjustable by one of the gears 19 and a bearing amplifier 21 in accordance with a sonar transducer bearing signal 43 derived from a synchro transmitter usually located in the sonars transducer dome.

A gas producing cartridge 22, e.g., a caliber .30 M3 rifle-grenade cartridge, loaded in the firing mechanism 10 is adapted to be fired by a solenoid 36 under the control of the sonar operator via a switch 44 to produce a gas pressure in the bore 23 of the barrel 11. This gas pressure acts on the bottom area of the tail tube of the projectile 12 to accelerate the projectile 12 along the barrel 11 to a velocity sufficient to obtain the desired range.

Variations in range of the projectile 12 are obtained by venting to the atmosphere some of the gas propellant through a conduit 24 providing a passageway connecting the bore 23 to an exit orifice 25 the effective area of which is varied by adjusting the position of a tapered plug 25 extending into the orifice 25, this latter assembly constituting an adjustable needle valve.

The tapered plug 26 is mounted on the distal end of a shaft 27 equipped with a lead screw thread 28 in threaded engagement with a nut 29 rigidly secured to the barrel 11. The shaft 27 as here shown comprises an extension of the shaft of a range control motor 30 which rotates the shaft 27 to move the tapered plug 26 toward or away from the orifice 25 to vary its effective gas venting area. The range control motor 30 has its shaft 27 connected through gears 45 to the adjustable element of a potentiometer 32. The settings of the ships sonar range cursor 31 and of the potentiometer 32 provide inputs to a range comparison network and amplifier 33 the output of which operates the range control motor 30 to position the plug 26 in accordance with a pre-selected calibration curve the preparation of which being not presently pertinent.

The bearing amplifier 21 and the range comparison network and amplifier 33 are preferably mounted within the cabinet 42. The sonar range cursor 31, the sonar transducer bearing signal source 43 and the firing switch 44 are located in the ships sonar room and are here shown as being a part of the sonar console 46.

The embodiment of the propellent gas venting arrangement shown in FIG. 2 has a tapered plug 35 (corresponding to the plug 26 in FIG. 1) the flat end of which forms a shoulder for holding a spring 34 seated between said shoulder and the facing end of the lead screw thread member 28. The tapered plug 35 is provided with a well 35' into which the end of the shaft 27 slidably extends a distance less than the depth of the well 35 so as to permit the spring 34 to deform, i.e., be compressed, under the force imposed by the gas pressure on the plug 35. Such deformation of the spring 34 allows the plug 35 to move away from the orifice 25 to thereby increase the venting area and provide a pressure regulating efiect with a consequent increase in accuracy because an increase in pressure from one cartridge over another will result in a greater venting area for the higher pressure cartridge. It may be noted that in each embodiment the venting orifice 25 faces a direction such that the thrust of the vented gas opposes the recoil thrust of the barrel 11.

It will be evident from the foregoing that the projectile launcher is automatically controlled in range and bearing and that since a sonar contact would be centered in the classification display at the time it is determined to be mine-like the classifying sonarman can press the firing switch 44 knowing that the launcher has the proper range and bearing settings.

Most propellent gases are quite dirty and known prior venting systems quickly gum up and require frequent cleaning. In the arrangement of this invention the taper on the plugs 26 and 35, respectively, divert the vented gas away from the lead threads 28 to prevent fouling and require very infrequent cleaning. In addition these threads 28 are readily accessible for cleaning whereas prior art valves generally required some dismantling for this purpose.

The rifle firing assembly has not been described in detail because it is a Model 1903 Springfield rifle having a single shot, bolt action mechanism with proven reliability and readily available to the government. The rifle has been modified by shortening its original barrel and adding a new barrel assembly fitted with the above described adjustable needle valve.

Although obvious to one skilled in this art it is to be understood that means such as mechanical stops will be provided to limit the rotation of the support arm 14 to that sector through which markers can be safely fired without hitting the superstructure of the ship and that safety switches will be provided, such as at the launcher, so that they must be closed before the closing of the switch 44 can actuate the launcher firing circuit.

While for the purpose of disclosing the invention specific embodiments thereof have been described, it will be evident to those skilled in the art that many modifications may be made in the system without departing from the invention the scope of which is pointed out in the appended claims.

What is claimed is:

1. In combination with a gun barrel having a longitudinal bore therethrough for the passage of the expanding gases generated upon the firing of a cartridge therein for propelling a projectile slidably mounted on the muzzle of the barrel,

conduit'means connecting said barrel bore to the atmosphere and having an orifice at its distal end, a tapered plug movable toward and away from said orifice for varying its effective gas venting area,

means including a pendulous weight for supporting said barrel at a fixed elevation with respect to the horizontal when a projectile is mounted on the muzzle of said barrel, and

means to adjust the position of said plug with respect to said orifice to produce variable venting of expanding gases in accordance with the range desired for said projectile.

2. The projectile propelling apparatus in accordance with claim 1 wherein said conduit means is so oriented that the thrust of the gases vented through the orifice of said conduit is in opposition to the thrust of the projectile propelling gases.

3. The apparatus in accordance with claim 1 wherein said tapered plug is spring mounted to allow limited movement of said plug away from said orifice to deform the spring as a direct function of the pressure of the propelling gases thereby compensating for variiations in the gas pressure produced by different cartridges.

References Cited UNITED STATES PATENTS 969,614- 9/1910 Florenz 8941 2,416,287 2/1947 Coates et a1. 421 2,417,983 3/1947 Holman et al 891 3,094,932 6/1963 Greenlees 89-28 X FOREIGN PATENTS 503,689 3/1920 'France.

SAMUEL W. ENGLE, Primary Examiner. 

1. IN COMBINATION WITH A GUN BARREL HAVING A LONGITUDINAL BORE THERETHROUGH FOR THE PASSAGE OF THE EXPANDING GASES GENERATED UPON THE FIRING OF THE CARTRIDGE THEREIN FOR PROPELLING A PROJECTILE SLIDABLY MOUNTED ON THE MUZZLE OF THE BARREL, CONDUIT MEANS CONNECTING SAID BARREL BORE TO THE ATMOSPHERE AND HAVING AN ORIFICE AT ITS DISTAL END, A TAPERED PLUG MOVABLE TOWARD AND AWAY FROM SAID ORIFICE FOR VARYING ITS EFFECTIVE GAS VENTING AREA, MEANS INCLUDING A PENDULOUS WEIGHT FOR SUPPORTING SAID BARREL AT A FIXED ELEVATION WITH RESPECT TO THE HORIZONTAL WHEN A PROJECTILE IS MOUNTED ON THE MUZZLE OF SAID BARREL, AND MEANS TO ADJUST THE POSITION OF SAID PLUG WITH RESPECT TO SAID ORIFICE TO PRODUCE VARIABLE VENTING OF EXPANDING GASES IN ACCORDANCE WITH THE RANGE DESIRED FOR SAID PROJECTILE. 